Fairly simple problem:
The total measure of a straight line is 180 deg so if we know lmn then we can find the measure of x pretty easily.
3x + 69=180
Now simplify:
3(x+23)=180
X+23 =60
X = 37
Now multiply x by 3 to find the measure of jml
3*37=111
Which makes sense cause 111+69 = 180